The present invention is directed to electromechanical apparatus for improving air flow through a duct system such as is commonly present in a home heating and air conditioning system.
Most homes that have forced air heating and air conditioning systems include only a single heating unit or furnace that commonly includes a plenum containing a heat exchanger and a refrigeration coil connected to an air conditioning unit. A single fan, operating in response to a single centrally placed thermostat, forces air to flow through a duct system that includes the furnace plenum. The duct system distributes the thermally treated air to various rooms of the home that are typically located at varying distances from the furnace. The length of duct work between the furnace and any given room of the home typically varies considerably, which causes the cooling and heating to occur preferentially in certain portions of the home.
It is known that enhanced uniformity in cooling and heating of a home can be achieved by equipping the home with multiple forced air heating and air conditioning units each of which is controlled by a thermostat located within a particular zone of the home. While such zone controlled systems operate very satisfactorily, they are generally substantially more expensive and cannot be economically justified in many circumstances.
It is also known to enhance the distribution of air through one duct of a duct system with the aid of a booster fan located in the duct work, often near or at a register end of the duct. Typically such fans are wired in conjunction with the furnace fan so that they are controlled by the same thermostat, and turn on and off with the furnace fan. It is also known, for example from U.S. Pat. No. 5,860,858, to control the operation of such a duct fan based on sensed air pressure within the duct. It is also known, for example from U.S. Pat. Nos. 4,576,331 and 5,632,677 to simply supply the fan with power on a continuous basis, and to control the supply of power to the fan with a thermostat located in the vicinity of the register.
The mechanical installation of such booster fans has typically been accomplished by inserting a special segment of ducting containing the booster fan as shown, for example, in U.S. Pat. No. 5,860,858. Such an installation typically requires tools to cut an existing segment from the duct work followed by sealing the new special segment in place within the duct work, often in very uncomfortable circumstances, such as in a crawl space under a home. To avoid such complex installation, both U.S. Pat. Nos. 4,576,331 and 5,632,677 disclose the alternative of simply replacing the existing register with a special register containing the booster fan. Unfortunately the known embodiments of such special registers have an unsightly appearance and are therefore undesirable.
What is needed is a booster fan mechanism that is easily installed without any special tools, yet is substantially invisible once it is installed.